1. Field of the Invention
This invention relates to reciprocating pump apparatus for converting solar and wind energy to mechanical energy.
2. Prior Art
A number of solar powered pump devices are known in the prior art. An example is U.S. Pat. No. 2,688,923 to Bonaventura, et al. for a solar energy pump using two alternatively heated boilers positioned on a common rocker arm, with the gas in one boiler being allowed to cool while the gas in the other boiler is being heated by the concentrated rays of the sun.
Sherock's patent, U.S. Pat. No. 3,112,862, for a reciprocating solar-driven device, uses the expansion force of a heated gas to force a piston upwardly against one or more downwardly directed forces, with the upward movement of the piston creating a partial vacuum within the piston central core that ultimately restores the piston to its lowest position.
U.S. Pat. No. 3,023,167 to Green combines a compressed, primary, moderate temperature gas with a secondary gas that has been highly heated by concentrated solar radiation, to produce an increase in enthalpy in the mixed gas and drive a turbine and a compressor.
A reciprocating thermal pump-compressor is the subject of U.S. Pat. No. 3,309,012 to Booth, et al. A volatile liquid is heated by the sun rays, and the resulting pressure from the evaporated gas causes an associated bellows to undergo a compression stroke and to do useful work. The created gas pressure is also utilized to move the volatile liquid out of the sun rays, thus allowing the liquid to cool and recondense. The resulting decrease in gas pressure causes the bellows to expand and produces a bellows suction stroke; the volatile liquid is moved back into the sun by a spring and another bellows combination, and another cycle begins.
U.S. Pat. No. Re. 27,740 to Schuman teaches the use of a reciprocating piston in a cylinder to pump a fluid, with gas in one end of the cylinder being continuously heated and increased in pressure by a heating source such as an electrical heating coil. The heated gas drives the piston in one direction as this gas is simultaneously drained by a check valve. The gas at the other end of the cylinder is compressed by the moving piston, acts as a pneumatic spring, and causes the piston to rebound by reversal of piston motion.
Thureau, et al., in U.S. Pat. No. 3,937,599, discloses a pump for drawing underground water, using solar energy to vaporize a volatile liquid, which displaces a deformable diaphragm in a two-part chamber. The vaporized liquid alternately fills and is exhausted from one of the motor subchambers, and the resulting diaphragm motion forces the flow of an incompressible liquid contained in the second motor subchamber; this in turn drives a pump that is submerged at a lower elevation in the water to be pumped. The Thureau, et al. invention requires a motor to convert differential fluid pressure to mechanical pressure (exerted on the liquid in the second motor chamber) and a pump that is in turn driven by this mechanical energy.
U.S. Pat. No. 3,972,651 to Kirsten for a solar-powered pump teaches the use of incident solar radiation to heat air being forced by its own pressure through a heat exchanger into a working chamber that communicates with a sump containing water at a given level. After the air pressure in the sump is "adequately increased", the sump water is forced through a discharge port and the process recycles. As the water enters the working chamber, the warm air is forced back into the expansion chamber to begin a new solar heating cycle.
A solar engine is disclosed in the U.S. Pat. No. 3,304,985 to Lapeyre, the invention in one embodiment being a wheel-like structure adapted for rotation about the wheel axis. The perimeter of the wheel contains a spaced sequence of double chamber cells, one closed chamber containing an expandible or volatile fluid, and the other chamber containing a non-expandible fluid and being in fluid communication with a conduit lying along the wheel circumference. Approximately one half of the cells are exposed to solar radiation, thereby heating the expandible fluid and forcing the non-expandible fluid out of the adjacent chamber into the conduit. The remaining cells are shielded from receipt of solar radiation and are cooled so as to receive additional quantities of the non-expandible fluid in the appropriate cell chambers. This causes a mechanical unbalance, and the wheel rotates and may perform useful work. This invention utilizes weight differentials rather than pressure differentials, developed within the irradiated cells.
Neidigh, in U.S. Pat. No. 3,989,417, teaches the use of a rotatable wheel with a sequence of piston assemblies mounted thereon and a narrowly directed solar radiation focusing means, to perform useful work through a high pressure fluid accumulator. Solar radiation is focused on one piston assembly, containing a volatile fluid at one end. The influx of heat causes the volatile fluid to expand and drive the piston in a first direction, thus forcing a second fluid in front of the piston into a high pressure fluid accumulator for subsequently performing useful (hydraulic) work. A motor then rotates the wheel to another position to expose another piston assembly and repeat the process. The expandible fluid in the first piston assembly now cools, and the piston is caused to retract in a second direction, opposite to the first direction, so as to fill the chamber in front of the piston with the second fluid for subsequent repetition of the work cycle. This invention requires the use of a motor or other device to rotate the wheel and of separate means to refill one chamber of each piston assembly with the second fluid.
A somewhat similar operation mechanism is taught by U.S. Pat. No. 4,041,707 to Spector for an underwater solar energy conversion unit, which exploits the difference between the surface temperature of a water body such as the sea, warmed by the sun, and the water temperature at the depth of immersion of the conversion unit. A piston or bellows is alternately driven back and forth by the air pressure difference developed in a variable temperature chamber and a constant temperature chamber. The unit drives an hydraulic pump which is also immersed in the body of water.
An object of the present invention is to devise a pump which uses both sun and wind energy synergistically to do useful work.